Somerset’s Ecological Network Mapping the components of the ecological network in Somerset 2015 Report This report was produced by Michele Bowe, Eleanor Higginson, Jake Chant and Michelle Osbourn of Somerset Wildlife Trust, and Larry Burrows of Somerset County Council, with the support of Dr Kevin Watts of Forest Research. The BEETLE least-cost network model used to produce Somerset’s Ecological Network was developed by Forest Research (Watts et al, 2010). GIS data and mapping was produced with the support of Somerset Environmental Records Centre and First Ecology Somerset Wildlife Trust 34 Wellington Road Taunton TA1 5AW 01823 652 400 Email: [email protected] somersetwildlife.org Front Cover: Broadleaved woodland ecological network in East Mendip Contents 1. Introduction .................................................................................................................... 1 2. Policy and Legislative Background to Ecological Networks ............................................ 3 Introduction ............................................................................................................... 3 Government White Paper on the Natural Environment .............................................. 3 National Planning Policy Framework ......................................................................... 3 The Habitats and Birds Directives ............................................................................. 4 The Conservation of Habitats and Species Regulations 2010 ................................... 6 The Natural Environment and Rural Communities Act 2006 ...................................... 6 3. Habitat Connectivity and Fragmentation ........................................................................ 7 Introduction ............................................................................................................... 7 Habitat Patches ......................................................................................................... 7 Fragmentation ........................................................................................................... 8 Species Dispersal ..................................................................................................... 8 Figure 1: Example of Fragmentation of a Metapopulation ............................................ 10 Scattered Resources ............................................................................................... 10 Connectivity ............................................................................................................ 10 Structural Connectivity ............................................................................................ 10 Functional Connectivity ........................................................................................... 11 Climate Change ...................................................................................................... 11 4. Ecological Networks ..................................................................................................... 12 Introduction ............................................................................................................. 12 Terms to Describe the Ecological Network .............................................................. 12 Table 1: Simplified Permeability Cost Scores ............................................................... 13 Components of Somerset’s Ecological Network ...................................................... 14 Figure 2: Areas in the Ecological Network .................................................................... 14 5. Modelling Somerset’s Ecological Network .................................................................... 16 Introduction ............................................................................................................. 16 BEETLE Least-cost Network Model ........................................................................ 16 Base Map ................................................................................................................ 17 Table 2: Somerset Habitat Map Data ........................................................................... 17 Home Habitat .......................................................................................................... 18 Table 3: Home Habitat Selection .................................................................................. 19 Generic Focal Species ............................................................................................ 22 Table 4: Summary of Generic Focal Species Metrics ................................................... 23 Landscape Permeability .......................................................................................... 23 Table 5: Summary of Permeability Cost Scores ........................................................... 24 Rivers and Streams Ecological Network .................................................................. 27 6. Outputs from the BEETLE Model ................................................................................. 28 Figure 6: Map of Somerset’s Ecological Network ......................................................... 28 Figure 7: Detail of Grassland Ecological Networks ....................................................... 29 7. Restoration of Ecological Networks .............................................................................. 30 Introduction ............................................................................................................. 30 Evaluating Ecological Networks .............................................................................. 30 Table 6: CORE Toolbox Ecological Network Evaluation Metrics .................................. 31 Restoration Actions ................................................................................................. 33 Selecting Restoration Areas .................................................................................... 34 Sustainable Use Areas ............................................................................................ 35 8. Development of Somerset’s Ecological Network .......................................................... 36 Introduction ............................................................................................................. 36 Network Validation .................................................................................................. 36 Habitat Survey......................................................................................................... 36 The Inclusion of Linear Features ............................................................................. 37 Wetland and Coastal Networks ............................................................................... 37 References ......................................................................................................................... 38 Appendix 1: Broad Habitat Descriptions ....................................................................... 46 Appendix 2: Information Informing the Development of Generic Focal Species ........... 50 Appendix 3: Woodland Species Data used for Generic Focal Species Development ... 53 Appendix 4: Species-rich grasslandSpecies used for Generic Focal Species Development ................................................................................................................ 67 Appendix 5: Heathland and Acid Grassland Species used for Generic Focal Species Development ................................................................................................................ 72 Appendix 6: Fen, Marsh and Swamp Species used for Generic Focal Species Development ................................................................................................................ 76 Appendix 7: River and Stream Species from the Somerset Priority Species List .......... 85 Somerset’s Ecological Network Summary As part of their efforts to tackle the on-going biodiversity decline in England, the coalition Government instituted reforms to the planning system which seek to embed ecological sustainability into the strategic planning and development management processes. Substantive changes have been made to the requirements placed on Local Planning Authorities to plan for nature through the National Planning Policy Framework, which mandates Local Planning Authorities to plan strategically for nature, identifying and mapping ecological networks in order to deliver the protection, enhancement and maintenance of biodiversity. Ecological networks are the basic, joined up infrastructure of existing and future habitat needed to allow populations of species and habitats to survive in fluctuating conditions. As a short term benefit, a landscape that species can move through easily allows recolonisation of areas after disturbance events, preventing local extinctions. In the long term, as our climate begins to change, well connected habitats offer opportunities for populations to move as conditions become more or less suitable. The movement of individuals between populations in a connected landscape maintains genetic diversity which allows populations to adapt to future changes in environmental conditions. In this document a set of ecological networks have been produced for four broad habitat types in Somerset: Broad-leaved Woodland; Priority Grasslands (including calcareous, acid and neutral grassland); Heathland and